How come I've never heard of the term MapReduce when using relational database (RDBMS)? And now suddenly with NoSQL MapReduce is everywhere. I would just like to understand in general sense why there's no MapReduce concept in relational database and why NoSQL needs it. Thanks.
为什么在使用关系数据库(RDBMS)时，我从来没有听说过MapReduce这个术语?现在NoSQL MapReduce到处都是。我只是想大体理解为什么关系数据库中没有MapReduce概念，为什么NoSQL需要它。谢谢。
2 个解决方案
#1
3
Judging by what the Wiki article you linked to has to say, MapReduce is an implementation technique. One of many possible others.
从你链接到的维基文章来看，MapReduce是一种实现技术。许多其他的可能性中的一个。
The relational model was invented precisely so that implementation techniques could be abstracted away from the user.
关系模型的发明是精确的，这样实现技术就可以从用户那里抽象出来。
It is quite telling that certain people now start "movements" that promote exposing the implementation techniques again to the user, and it is even more telling that they call that "progress".
很明显，某些人现在开始“运动”，以促进将实现技术再次公开给用户，更说明问题的是，他们称之为“进展”。
People who know and understand the relational model, also understand that in a truly relational DBMS, there is nothing to stop the engine from applying exactly those very same MapReduce techniques under the covers, when dealing with "BigRelations".
了解并理解关系模型的人也知道，在真正的关系DBMS中，当处理“bigreations”时，没有什么可以阻止引擎在幕后使用完全相同的MapReduce技术。
#1
3
Judging by what the Wiki article you linked to has to say, MapReduce is an implementation technique. One of many possible others.
从你链接到的维基文章来看，MapReduce是一种实现技术。许多其他的可能性中的一个。
The relational model was invented precisely so that implementation techniques could be abstracted away from the user.
关系模型的发明是精确的，这样实现技术就可以从用户那里抽象出来。
It is quite telling that certain people now start "movements" that promote exposing the implementation techniques again to the user, and it is even more telling that they call that "progress".
很明显，某些人现在开始“运动”，以促进将实现技术再次公开给用户，更说明问题的是，他们称之为“进展”。
People who know and understand the relational model, also understand that in a truly relational DBMS, there is nothing to stop the engine from applying exactly those very same MapReduce techniques under the covers, when dealing with "BigRelations".
了解并理解关系模型的人也知道，在真正的关系DBMS中，当处理“bigreations”时，没有什么可以阻止引擎在幕后使用完全相同的MapReduce技术。